The formation of decubitous ulcers, commonly known as bed sores, results from, amongst other things, the pressure applied to certain portions of the skin of a bedridden patient. It is known to meet the requirement for the prevention and management of decubitous ulcers with an alternating pressure pad comprising two series of inflatable cells which are interleaved, one series within the other, the cells alternately inflated to support a patient at different locations. Typically, inflation and deflation cycles may last from under two minutes for a gentle massaging effect to over twenty minutes.
Typically, large cells have been used in the form of an elongate cylinder extending linearly straight across a pad. However, these pads have experienced problems in that the alternating inflation and deflation of adjacent cells tends to induce movement of the user down the pad, requiring the user to be manually re-positioned by a nurse or carer. This movement is uncomfortable to the user and areas of the body that require pressure relief from a deflated cell are moved onto an inflated cell resulting in reduced pressure relief for the user.
A further disadvantage encountered with such cells is that a user's bony protuberances, for example, their heels can fall inbetween the inflated cells and rest on the support beneath, therefore experiencing the high pressures likely to cause pressure sores. Furthermore, as the support backrest or pillows are raised to support the user in a seated position, the cells have tended to rotate and separate out under the user's sacrum resulting in the user bottoming and resting on the support beneath the pad.
It is known to have non-linear cells, but there is still some movement of the user down the pad and also rotation of the cells during support of the user in the seated position. Furthermore, the non-linear cells are difficult to manufacture with problems of creases within their inner curvature compromising their pressure relief performance.